Self-propelled crawler-type mobile platform



Aug. 27, 1968 A. L. HENDRICKS -TYPE MOBILE PLATFORM SELF-PROPELLED CRAWLER 2 Sheets-Sheet 1 Filed May 12, 1966 F|G Z FIG I INVENTOR.

ATTORNEYS 7, 1968 A. L. HENDRICKS 3,398,806

SELF-PROPELLED CRAWLER-TYPE MOBILE PLATFORM Filed May 12, 1966 2 Sheets-Sheet z INVENTOR. ALVIN L. HENDRICKS ATTORNEYS United States Patent 3,398,806 SELF-PROPELLED CRAWLER-TYPE MOBILE PLATFORM Alvin L. Hendricks, 16445 11th SW.,

' Seattle, Wash. 98166 Filed May 12, 1966, Ser. No. 549,715 Claims. (Cl. 180-2) ABSTRACT OF THE DISCLOSURE A mobile platform comprised of two matching individually powered crawler-type dollys rigidly tied together in rather widely space side-by-side relation by a spanner member serving as a load-carrying deck, and individually controlled as to direction and speed of drive from a position remote to the platform.

This invention relates to a self-propelled crawler-type mobile platform for use in moving loads, particularly loads such as construction materials which have been previously delivered to a job site and which it is desired to distribute to the workmen.

Background of invention The need for a vehicle of the character and for the purpose described is particularly evidenced on a job such, for example, as an industrial roof in which metal deck ing sheets--usually ribbed or corrugated and supplied in various lengths and gauges to meet differing specifications-are laid down as a sub-roof. Cranes are commonly employed to lift a pile of the decking sheets onto the roof,

providing the source from which workmen draw a supply of sheets as the deck takes shape. On the roof, for the lack of any power equipment capable of efiiciently moving the sheets from the supply pile to the workmen who are laying the sheets, it has been the practice heretofore to carry the sheets by hand. Two men can pack no more than a few sheets, and in their travel over the previously laid decking must walk with considerable care if such decking is not to be damaged. It is this liability to damage, bearing in mind that the surface of a corrugated or ribbed sheet presents alternating ridges and valleys, which precludes the use of wheeled trucks to carry the sheets.

It is one object of the present invention to provide a self-propelled platform of the crawler type, which is enabled to carry comparatively heavy loads over surfaces such as a ribbed or corrugated sub-roof, with no liability of damage to the roof. It is a further object to provide such a mobile platform, characterized in that the width can be increased or decreased at will with ease and expedition. As a yet further object the invention aims to provide a mobile platform of the described character which can be remotely controlled by an operator walking or standing alongside the path travelled by the platform. These and yet additional objects and advantages in view will appear and be understood in the course of the following description and claims.

Description of drawings In the accompanying drawings:

FIGURE 1 is a perspective view illustrating a mobile platform constructed to embody preferred teachings of the present invention and shown moving sheets of metal decking over a sub-roof which is in process of being laid.

FIG. 2 is a fragmentary end elev-ational view detailing one of the two matching dollys which serve as the traction components for the platform and incorporating a fragmentary part of the connecting structure which joins the two dollys.

FIG. 3 is a longitudinal vertical sectional view on line 33 of FIG. 2.

Patented Aug. 27, 1968 4 is a horizontal sectional view on line 44 of FIG. 3, with the crawler track partly broken away to expose parts which would otherwise be concealed.

.. ..FIG.. 5 is an underside plan-view, and with the crawler track shown fragmentarily; and

FIG. 6 is a perspective view of the dolly-controlling switch box.

Description of invention Broadly considered, the platform of the present invention comprises a span of two matching dollys disposed in rather widely spaced side-by-side relation and harnessed one to the other in such a manner that the two dollys move as one and each serve as a respective one of the two traction sides of a utility vehicle. The dollys are powered individually from separate coordinated motors, and are crawler-type with the lower, iQe. traction, runs of their endless tracks constrained to a level travel.

In view of the matching nature of the dollys a'description of one will suffice for the other. Referring to said drawings the treads 20 for the endless tracks are formed as flights upon the links 21 of a traction chain and are flat other than for being turned up in a moderate degree at the ends. The traction surfaces are coated with epoxy rubber. Measured from one to the other side edge the treads are quite long, say 13", and their width, front edge to back edge, approximately corresponds to the centerto-center 'spacing of pins 22 which pivotally connect the links. The chain is trained over front and rear sprocket wheels 23-24 fixed the latter to a live axle 25 and the former to a free-running axle 26. The sprocket wheels lie on the longitudinal median line of a channel-shaped main frame member 27 and have their axles journaled in boxes which are bolted to the cheek-plates which said frame member provides. The cheek-plates are yoked adjacent each of the two ends by weld-attached channel-iron members 28 having an inverted-U profile configuration. For a purpose which will hereinafter appear the cross-arms of the yoking members are rigidly surmounted by a sleeper 30 which parallels the plane in which the sprocket wheels lie. The sleeper is made from angle-iron stock so that one flange lies parallel to the ground and produces a shelf from which the other flange rises as a back wall. The live axle 25 has a driven sprocket wheel 32 fixed thereto at one side of the traction sprocket wheel 24. A reversible electric motor 35 supported from the frame acts through the gears of a reduction gear box 36 to drive a sprocket wheel 37, and a chain 38 passes a reduction drive from the driving wheel 37 to the driven wheel 32. I

The bottom plate 29 of the 'main frame member 27 has re-entrant centered slots at each of the two ends. The traction sprocket wheels 23 and 24 protrude through these slots in a degree sufiicient to place the lower or traction run of the crawler track well below such bottom plate. Accommodated in the space which is thereby provided, and bearing upon the upper faces of the traction treads as they traverse said lower run, are longitudinal rows of free-turning rollers 41. Two of said rows are provided at each side of center. The rollers are or may be composed of hard rubber and are moderately long to provide a substantial bearing surface. Being formed to a small diameter, say 2", with no more than bare clearance between any two rollers in a row, and having the rollers of one row staggered relative to those of the adjacent row, the rollers produce a thrust-taking friction-free guide surface which to all intents and purposes has a flat profile. The traction run of the treads is constrained by said guide surface to a level travel. At the infeed and the outfeed extremities of said traction run, where the lead edge and the trailing edge, as the case may be, of a tread would otherwise bear only against two rollers, as distinguished from the minimum of four rollers which take the upward thrust of the treads through their interim travel, each terminal roller is augmented by a roller 42 occupying a position between the two rows. Channel members 43 are welded to the underside of the bottom plate 29 as journal mountings for the guide rollers.

In harnessing the two complementing dollys, a squareend floor piece 44, and which by preference is comprised of one of the sheets of steel decking which is being laid, is applied between the dollys with its squared ends resting upon the shelf portion of the related sleeper 30. Each sleeper has a section 45 of chain anchored to a ring 39 which is welded to the underside, and free ends of the two chain sections are interconnected by attaching same to the opposite ends of an intervening puller device. As here illustrated the puller device includes an overcenter lever 46 (FIG. 1). By tensioning the chain sections against the resistance, endwise to the length, imposed by the floor piece 44 as the squared ends of the latter are brought against the back walls of the two sleepers 30, the floor performs the function of a cross-strut while the connected chain sections serve as a cross-tie. Substantially any length of floor piece can be used, in that loose slack is taken up by hooking the ends of the detached puller device to selected links of the chain sections.

Each of the two electric motors 35 which drive the dollys are supplied with current through comparatively long cables 47 and 48 leading from a switch box adapted to be carried by and under the control of an operator. The box has separate 3-position (forward, off, reverse) switches 51 and 52 for the two motors. Power to the switches is or may be supplied through a long feed cable 53 from a portable 220 v. gas-powered generator 54.

The connected span of dollys will follow a straight course when the two switches are both placed in either a forward or in a reverse position. Steering is easily accomplished by manipulation of the switches, ie by placing one switch in the off position while power continues to feed to the motor of the other dolly. The connected span of dollys will turn within its own width by operating one motor in reverse and the other in forward".

It is thought that the invention and the manner of its usage will have been clearly understood from the foregoing detailed description of my now-preferred illustrated embodiment. While accomplishing their greatest usefulness when harnessed as a connected span, there are perforce operations in which a single dolly has usefulness separate and apart from the other. I intend that no limitations be implied and that the hereto annexed claims be given the broadest interpretation to which the employed language fairly admits.

What is claimed is:

1. A mobile platform comprising, in combination: two matching dollys disposed in spaced-apart side-by-side relation with each dolly having a main frame and being provided with an endless crawler track and a motor for driving the track, a cross-connection tying the two frames rigidly together and producing a load-carrying deck elevated above ground level, and a means under the control of an operator for individually governing the direction and the speed of the two motor-driven tracks from a position common to both dollys, the frames each providing a horizontal shelf and an upright wall along the back of the shelf extending parallel to the longitudinal median line of the related dolly, the cross-connection comprising a tensioning tie-member and a square-ended spanner resting by its ends upon the two shelves and by a tensioning take-up of the tie member brought to bear against the upright walls to perform the office of a strut.

2. A mobile platform as claimed in claim 1, the main frames including yokes of an inverted-U profile configuration located adjacent each of the two ends of the dolly with the cross-arms of the yokes overlying the upper run of the crawler track and connected, one crossarm with the other cross-arm, by a longitudinal stringer. which produces said shelf.

3. A mobile platform as claimed in claim 1, in which the load to be carried is sheets of metal roof decking, the spanner comprising a sheet of said decking matching, in point of its end profile configuration, the indlvidual components of said load.

4. In dolly construction, a main frame comprised of a wide channel member facing upwardly so that a floor is provided at the bottom with cheek plates rising from each side edge thereof, the floor having longitudinally extending in-line slots at the two ends, front and rear sprocket wheels carried by said check plates of the main frame for rotation about transverse horizontal axes with their bottom portions protruding through the slots, an endless crawler tr-ack trained over said sprocket wheels and in its lower-run travel between the wheels providing traction for the dolly, a motor mounted on the frame to occupy a position between said cheek plates and operatively connected with the crawler track for driving the track, the flights of connected chain links which produce said endless track having flat interior faces which are spaced below the floor of the main frame in said lowerrun travel of the track, and means supported from the floor of the main frame bearing upon said interior faces of the chain flights to proscribe for the track a guidedlevel path of lower-run travel paralleling the floor.

5. Dolly construction as claimed in claim 4, said bearing means comprising plural longitudinally extending rows of free-turning close-mounted rollers bearing upon the upper face of the treads which compose the endless tracks and characterized in that the rollers are of small diameter and longitudinally staggered as between the rollers of one row and those of a next adjacent row, the support for said rollers comprising a respective longitudinally extending downwardly facing channel piece for each row.

References Cited UNITED STATES PATENTS 741,938 10/1903 Sell 305-17 1,140,969 5/ 1915 Eastman 30528 1,222,295 4/1917 Jett 30528 2,138,485 11/1938 Faries 214350 2,686,697 8/ 1954 Baker.

2,832,481 4/1958 Stevens 21438 3,074,499 1/ 1963 Bertelsen -962 3,148,921 9/ 1964 Batur et al. 30535 3,205,961 9/1965 Nolte 1809.48

FOREIGN PATENTS 986,180 3/1965 Great Britain.

LEO FRIAGLIA, Primary Examiner. 

